Sulfur dioxide in the atmosphere of Venus 1 sounding rocket observations

In this paper we present ultraviolet reflectance spectra obtained during two sounding rocket observations of Venus made during September 1988 and March 1991. We describe the sensitivity of the derived reflectance to instrument calibration and show that significant artifacts can appear in that spectrum as a result of using separate instruments to observe both the planetary radiance and the solar irradiance. We show that sulfur dioxide is the primary spectral absorber in the 190 - 230 nm region and that the range of altitudes probed by these wavelengths is very sensitive to incidence and emission angles. In a following paper Na et. al. (1994) show that sulfur monoxide features are also present in these data. Accurate identification and measurement of additional species require observations in which both the planetary radiance and the solar irradiance are measured with the same instrument. The instrument used for these observations is uniquely suited for obtaining large phase angle coverage and for studying transient atmospheric events on Venus because it can observe targets within 18 deg of the sun while earth orbiting instruments are restricted to solar elongation angles greater than or equal to 45 deg

The AEPEX CubeSat Mission: Quantifying Energetic Particle Precipitation through Bremsstrahlung X-Ray Imaging

Fundamental gaps exist in the understanding and observation of energetic particle precipitation (EPP),a solar-terrestrial coupling mechanism that is vital for climatelogical modeling of the atmosphere and magnetosphere. The Atmospheric Effects of Precipitation through Energetic X-rays (AEPEX) mission is a 6U CubeSat that will measure energetic electron spectra and X-ray images in order to quantify the spatial scales and amount of energy input into the atmosphere, and therefore lost from the magnetosphere, via EPP. AEPEX includes two instruments; AEPEX’s FIRE (Focused Investigations of Relativistic Electron) instrument (AFIRE), a TRL 9 electron detector previously flown on the FIREBIRD mission; and the Atmospheric X-ray Imaging Spectrometer (AXIS), an instrument being developed at CU Boulder that will take novel images and spectra of 50–300 keV X-ray photons. This work describes the AEPEX mission overview, the detailed design and operation of AXIS, and initial test and calibration results

The AEPEX Mission: Imaging Energetic Particle Precipitation Into Earth’s Upper Atmosphere

Radiation belt electron fluxes can be enhanced during geomagnetic storms by two orders of magnitude; subsequently, these fluxes decay back to nominal levels in a few days. Precipitation into the upper atmosphere is a primary loss mechanism for these electrons, particularly during the decay phase. Upon impacting the upper atmosphere, these electrons create new ionization, leading to a chemical response that increases NOx and HOx and destroys ozone. Quantifying both radiation belt loss and the impact on the atmosphere requires an accurate estimate of the flux, energy spectrum, and spatial and temporal scales of precipitation. The NASA-funded Atmospheric Effects of Precipitation through Energetic X-rays (AEPEX) Cube-Sat mission is designed to quantify these parameters of radiation belt precipitation by measuring the bremsstrahlung X-rays created during the precipitation process, using a new instrument called the Atmospheric X-ray Imaging Spectrometer (AXIS). Hard X-rays (50-300 keV) emitted by Earth’s atmosphere have previously been measured from high-altitude balloons and satellites, but have never been imaged from space. The AXIS instrument will image the X-ray fluxes produced by the atmosphere, providing measurements of spatial scales, along with the X-ray flux and spectrum, using off-the-shelf pixelated detector modules and coded aperture optics. A solid-state energetic particle detector, with heritage from the FIREBIRD Cube Sat mission, will measure the precipitating electron energy spectrum, which is used to constrain the inversion from X-ray fluxes to electron fluxes. The AEPEX spacecraft is a 6U CubeSat, currently being built by the University of Colorado Boulder. It includes a custom-designed structure and a custom spacecraft bus consisting of an electrical power system, command and data handling, flight software, and instrument interface electronics designed by the Laboratory for Atmospheric and Space Physics (LASP) at CU Boulder. The system also includes custom-designed doubly-deployable solar panels. The mission will be launched into ahigh-inclination orbit to ensure coverage of high latitudes; launch is scheduled for early 2024

Togo: Thorny transition and misguided aid at the roots of economic misery

The parliamentary elections of October 2007, the first free Togolese elections since decades, were meant to correct at least partially the rigged presidential elections of 2005. Western donors considered it as a litmus test of despotic African regimes’ propensity to change towards democratization and economic prosperity. They took Togo as model to test their approach of political conditionality of aid, which had been emphasised also as corner stone of the joint EU-Africa strategy. Empirical findings on the linkage between democratization and economic performance are challenged in this paper because of its basic data deficiencies. It is open to question, whether Togo’s expected economic consolidation and growth will be due to democratization of its institutions or to the improved external environment, notably the growing competition between global players for African natural resources

Colorado Ultraviolet Transit Experiment: a dedicated CubeSat mission to study exoplanetary mass loss and magnetic fields

The Colorado Ultraviolet Transit Experiment (CUTE) is a near-UV (2550 to 3300  Å) 6U CubeSat mission designed to monitor transiting hot Jupiters to quantify their atmospheric mass loss and magnetic fields. CUTE will probe both atomic (Mg and Fe) and molecular (OH) lines for evidence of enhanced transit absorption, and to search for evidence of early ingress due to bow shocks ahead of the planet’s orbital motion. As a dedicated mission, CUTE will observe ≳100 spectroscopic transits of hot Jupiters over a nominal 7-month mission. This represents the equivalent of <700 orbits of the only other instrument capable of these measurements, the Hubble Space Telescope. CUTE efficiently utilizes the available CubeSat volume by means of an innovative optical design to achieve a projected effective area of ∼28  cm^2, low instrumental background, and a spectral resolving power of R∼3000 over the primary science bandpass. These performance characteristics enable CUTE to discern transit depths between 0.1% and 1% in individual spectral absorption lines. We present the CUTE optical and mechanical design, a summary of the science motivation and expected results, and an overview of the projected fabrication, calibration, and launch timeline

Drivers of Change or Cut-Throat Competitors? Challenging Cultures of Innovation of Chinese and Nigerian Migrant Entrepreneurs in West Africa

L'afflux remarquable des entrepreneurs migrants chinois dans différents pays d'Afrique occidentale au cours des dernières années a été heurtée à une résistance de plus en plus farouche par des entrepreneurs locaux établis. Que le premiers ont un avantage concurrentiel sur ce dernier en raison de traits socio-culturels distinctifs, ou si l'efficacité supposée chinoise est juste une caractéristique de toutes les diasporas mercantiles, est ouvert à la question. Cette étude exploratoire des migrants entrepreneuriales chinois et nigérians au Ghana et au Bénin tente de répondre à cette question. Apparemment, les forces culturels des agents du changement migrants ne sont pas limités à des systèmes de valeurs héritées ou religions, comme une éthique protestante ou le confucianisme, mais ils sont adaptés en permanence et ont inventé de nouveau par des réseaux transnationaux de la migration dans un monde globalisé. Il n'y a aucune preuve d'une prétendue supériorité de la culture d’innovation chinois par rapport aux cultures d’innovation africains des migrants entrepreneuriales. Plutôt, il existe une capacité accrue d'innovation d'une diaspora mercantile en général vis à vis des entrepreneurs locaux, indépendamment de l'origine de la culture nationale dans lequel il est intégré. En outre, la rivalité des entrepreneurs migrants chinois et nigérians dans les marchés africains ne conduit pas nécessairement à la concurrence coupe-gorge souvent suspectée sous l'impact de la mondialisation. Souvent, les deux groupes agissent plutôt complémentaires. Cela contribue, sous certaines conditions, même à la réduction de la pauvreté dans le pays d'accueil